Basic mechanisms of mammalian cell modulation in vitro by nonthermal radiofrequency radiation exposure will be investigated. Knowledge of interaction mechanisms is essential to assessments of beneficial exposure effects, such as wound healing or immunostimulation, as well as deleterious effects such as the promotion of neoplasia. Interaction mechanisms will be investigated by exposing cells (human peripheral lymphocytes, glioma, and Chinese hamster ovary [CHO]) under isothermal conditions (37+/-0.2degree) to RF radiation doses that were shown to modulate proliferation. Responses will be characterized by studying RF effects on mitogenic activation of T-lymphocytes, including the induction of interleukin 2(IL-2) and IL-2 receptors. RF effects on transcription and translation will be characterized in terms of stress protein induction. Synchronized CHO cell cultures will be exposed to RF to determine cell-cycle dependent effects on proliferation. These data will be used in conjunction with theoretical determinations of RF-induced electromagnetic fields in cells to test the hypothesis that the plasma membrane is the primary interaction site. The long-term objective will be to test the hypothesis that the basic interaction of RF radiation is with cell bound (vicinal) water. This will be investigated by high frequency dielectric spectroscopy and proton nuclear magnetic resonance spectroscopy of synchronized cell cultures. These techniques will also be used to investigate the effects of RF radiation on cell bound/free water using synchronized and random phase cells exposed under isothermal conditions that are known to affect cell proliferation.